The present invention relates to electrical power control and, more particularly, to the automated control of power to a load A major objective of the invention is to conserve energy usage by vending machines.
Recent events have given urgency to what has always been a good idea: energy conservation. Energy conservation can be implemented simply by turning off power from appliances that are not in use. While power control can be done manually, e.g., people can turn off appliances when they are done using them and turn off lights as they leave a room, automated power control plays an important role in energy conservation.
Timers can be used to control power delivery. For example, business lights can be turned on automatically at the start of a business day and turned off automatically at its close. Alternatively, timers can control the duration for which an appliance is active. For example, a timer might turn off a hot-air hand dryer after a fixed time; anyone wanting more time can reset the hand dryer. Many appliances, such a printers, enter a low-power xe2x80x9csleepxe2x80x9d mode after a set period of non-use.
Ambient-light sensors can be used to control certain appliances. For example, street lamps can be activated in low-light conditions, and deactivated when morning brings sufficient light that the artificial illumination is not required. Motion sensors, such as occupancy sensors, can be used to supply power only when people are present. Security lights often combine ambient-light detection and motion detection. During the day, the lights remain off regardless of motion in their vicinity; however, at night, motion triggers the lights on.
Vending machines, particularly those that are refrigerated, pose special problems when it comes to energy conservation. Typically, a vending machine owner-operator places a vending machine in operation on the premises of another, and visits as necessary to refill the vending machine. The owner of the premises typically pays for the electricity consumed by the vending machine, and thus may have the biggest interest in saving power; however, the premises owner may be limited to unplugging the vending machine to save power during time of low usage.
However, unplugging or switching off a refrigerated vending machine can have the undesirable consequence that the vending items may warm up. In extreme cases, this may cause items to spoil. However, even where spoilage is not a problem, customers might have the unpleasant experience of, for example, a warm soda if they purchase soon after the vending machine is turned on. Also, unplugging or switching off a vending machine risks losing sales and customers.
Copending U.S. patent application Ser. No. 09/579,411 discloses a vending machine with active and power-conservation modes. An occupancy sensor can be used to activate the system from power-conservation mode when a potential customer is in the vicinity. The cooling strategy ensures that a customer obtaining an item, even after a power-conservation period, will receive a properly chilled item. Thus, sales and customer satisfaction are maintained.
One issue regarding the active and power-conservation modes for a refrigerated vending machine is what to do with panel lights. Many vending machines include panel lighting to attract the attention of potential customers and indicate that the vending machine is operational. If the panel lighting is off in a power-conservation mode, fewer potential customers will be drawn to purchase from the vending machine. On the other hand, if the panel lighting remains on during power-conservation mode, the energy savings will be less than it could be. So there remains an issue of how to control vending machine panel lighting to optimize the tradeoff between functionality and energy-conservation.
The present invention provides an appliance with a power conservation scheme that takes both location (indoor versus outdoor) and ambient light into account in controlling a load. In the context of a vending machine, the load can be the panel lighting. In the context of a refrigerated vending machine, the power-conservation scheme for the panel lighting is distinct from the power-conservation scheme for the cooling system.
The indoor-versus-outdoor determination governs how ambient light is used to control panel lighting. If the room that the vending machine is in is dark, it is usually unoccupied; since no potential customers are present, power can be withheld from the lights to conserve energy. Potential customers are more likely to be present if the room is artificially illuminatedxe2x80x94especially if conservation measure is in place for room lighting. Accordingly, power is supplied to the panel lights in the context of indoor lighting. For situations where a room remains lit even when it is unoccupied for extended periods of time, an occupancy sensor can be used to turn of panel lights after a predetermined duration of vacancy.
If the machine is outdoors, the relatively bright conditions even in the shade can xe2x80x9cwash outxe2x80x9d panel lighting; to save energy, power can be withheld from the panel lighting under bright outdoor conditions. However, when it is dark outside, power can be supplied to the panel lighting to attract potential customers.
The indoor-versus-outdoor determination can be made in several ways. The simplest method is to have an operator (human) set the indoor-versus-outdoor mode, for example, as part of the vending machine installation procedure. However, automatic indoor-versus-outdoor location can be detected automatically as well. For example, very bright maximum ambient light can be used to indicate outdoor conditions. Alternatively, color temperature can be used to distinguish natural (outdoor) and artificial (indoor) lighting sources; sunlight tends to be relatively blue, while incandescent lights tend to be relatively red and fluorescent lights tend to be relatively green. In a preferred realization, an operator can select among indoor, outdoor, and automatic modes. The default is automatic mode, so if the operator neglects to select a mode, correct determination of location mode is still probable.
The present invention provides enhanced energy conservation for a refrigerated vending machine, as well as other devices. Since the panel lights can be controlled separately from the cooling system of a refrigerated vending machine, the lights can be on while the cooling system is conserving power and the cooling system can be cooling while the lights are off. This allows the energy-conservation to be optimized separately for the lights and the cooling system, for greater overall conservation.
Location detection allows outdoor operation to be, in a sent, inverted from indoor operation. Outdoors, the lights are on when the ambient is dark, while, indoors, the lights are off when the ambient is dark. Thus, power conservation for the panel lights is optimized for each location. These and other features and advantages of the invention are apparent from the description below with reference to the following drawings.